This chapter explores distinct views about the conditions under which life is worth extending. The first section examines the view that whether living longer is good or bad is contingent upon the kind of experience life is. The metaphor of life as an experience machine brings out the philosophical assumptions inherent in variations on this theme. Limitations of the experience view suggest the need to formulate alternative accounts that refer to objective human capabilities, authenticity, or being in synch with reality. The second section explores how these different assessments of life's value inform practical judgments about whether to offer or accept lifesaving interventions for persons with dementia, focusing on surrogate decision-making for individuals with Alzheimer's disease.